1. Field of the Invention
This invention relates to a thermal conductive member for connecting a heat-generating device to a heatsink serving to radiate heat generated by the heat-generating device, and also relates to an electronic device employing this thermal conductive member.
2. Description of the Related Art
It is a common practice in the art to mount a heatsink on a semiconductor device (e.g. a discrete device such as a power transistor and an integrated circuit device such as a microprocessing unit (herein-after referred to as "MPU")), which generates a large quantity of heat, in order to cool this heat-generating device. In this case, in order to enhance the intimate contact between the heatsink and the heat-generating device, a paste-like thermal conductive member, such as silicone grease, or a sheet-like thermal conductive member with good thermal conductivity and elasticity, such as silicone rubber, is interposed between the heat-generating device and the heatsink.
A conventional thermal conductive member will be described below. FIG. 6 is a cross-sectional view of an electronic device using a conventional thermal conductive member. In FIG. 6, reference numeral 8 denotes a semiconductor device (heat-generating device), reference numeral 9 a heatsink for radiating heat generated by the heat-generating device 8, and reference numeral 10 a thermal conductive member interposed between the semiconductor device 8 and the heatsink 9 to enhance the intimate contact therebetween. The thermal conductive member 10 is required to have the high ability of intimate contact with and high thermal conductivity to the heat-generating device 8 and the heatsink 9, and silicone grease, silicone rubber and the like have heretofore been used as the thermal conductive member.
However, the conventional thermal conductive member, comprising silicone grease or silicone rubber, has the following problems.
The paste-like thermal conductive member, such as silicone grease, can fill a fine gap, and therefore can achieve a high degree of thermal conductivity. However, this thermal conductive member is in the liquid state, and therefore a control must be effected for applying a predetermined amount of coating. And besides, when the heatsink 9, once removed from the heat-generating device 8, is to be again mounted thereon, the paste-like thermal conductive material must be additionally coated. Thus, there has been encountered a problem that the handling of the paste-like thermal conductive member is rather troublesome. The sheet-like elastic thermal conductive member, such as a silicone rubber sheet, can be handled easily, and when mounting a heatsink to a low-strength package such as a semiconductor device of a tape carrier package (hereinafter referred to as "TCP"), a concentrated stress will not act on the semiconductor, which is advantageous. However, there has been encountered a problem that the sheet-like thermal conductive member is lower in thermal conductivity than silicone grease or the like.